1. Technical Field of the Invention
The present invention discloses a two-dimensional (2D) product code for forward error correction (FEC) and a method for detecting false decoding errors in digital communication systems.
2. Background of the Invention
Long-distance digital communication systems, such as optical submarine cable systems, are responsible for the transmission of significant amounts of data. This data is transmitted across great distances, often from continent to continent. During transmission, data can become corrupted from noise within transmission channels, faults in transmission or receiving devices, or data errors from reading from and writing to an elastic store. Therefore, FEC is employed to minimize the error probability of transmitted data.
Claude Shannon first suggested a maximum possible channel throughput which developed into a theorem of error correction describing the addition of redundant data to payload data for the correction of errors from channel noise or interference during transmission. This FEC increases the reliability of transmitted data by encoding a block of payload data with redundant data bits through an algorithm generated at the transmitter, which allows a decoder to determine if an error has occurred. The decoder employs the code generated by the encoder to identify what information, if any, has been corrupted by noise or interference during transmission, and the decoder can in turn correct these errors.
As known in the art, FEC can be implemented as a product code. A product code may be two-dimensional (2D), where every bit within the transmission frame is subject to two separate, but intersecting, codes; one row code and one column code. A FEC codeword (n), or block of symbols, is comprised of data bits or information symbols (k) and parity bits or redundant symbols (r). Generally, any errors in long-distance data transmission are uniformly random. Such errors can be remedied by interleaving bits for transmission; therefore, errors are scattered across transmission frames so that de-interleaving the data shows random, individualized errors which are easy to detect and correct.
Presently, prior art teaches the use of cyclical redundancy check (CRC) codes to detect false errors. However, appending CRC parity to the data increases both the overhead and the redundancy of the system. Therefore, it is an object of the present invention to provide a method to detect and correct false errors without the use of CRC codes.